Uber executives believe the software designed to prevent the car from overreacting to insignificant hazards wasn’t dialed in properly, according to the sources, which the outlet described as “two people briefed about the matter.”

As a result, the system, which normally flags ― then dismisses ― things like plastic bags and other minor obstacles, decided not to take evasive measures when it encountered 49-year-old Elaine Herzberg, who was walking her bike across a dark section of road in Tempe.

The vehicle was going 38 mph in a 35 mph zone and didn’t swerve or slow down as it approached Herzberg, according to the police report from the time. She was taken to a local hospital, where she died of her injuries. Camera footage from inside the car shows the backup driver was distracted and not looking at the road when the accident happened.

Uber suspended all of its self-driving car operations following the accident.

Mike Ramsey, a transportation and mobility analyst at Gartner Inc., told Bloomberg at the time that there are only two real explanations for the accident: Either the vehicle suffered a technical failure and didn’t detect Herzberg at all, or it identified her, but “the decision-making software decided that this was not something to stop for.”

The information reported Monday rules out the first explanation. And that’s not a good thing for Uber, as the second is the more difficult problem to solve. As a driver, it doesn’t matter how great your eyesight is if you can’t make real-time decisions to safely navigate the environment.

The National Transportation Safety Board immediately sent a team to Tempe to conduct an investigation after the death but has yet to release any findings. The NTSB didn’t immediately respond to a request for comment on Monday’s report.

An Uber spokeswoman referred HuffPost to the NTSB for all questions related to the incident and the findings of its investigation. In an emailed statement, Uber added that it recently hired former NTSB Chairman Christopher Hart to review its safety procedures.